This invention relates to conveyor apparatus, and, more particularly to conveyor and feed control apparatus for controlling the movement of articles (such as a stack of flat annular can ends) in a conveying conduit.
Diverse types of industries utilize conveying conduits such as tubular conveyors or chutes to transport various articles. In the manufacture and packaging of aluminum cans for instance, conveying apparatus having conduits are often used to transport can closure ends, and to feed the ends into various machines for performing operations such as seaming, bagging, or testing of the ends. The conduits are often formed from spaced parallel elongated rods which are welded to support struts to form a conduit passage having a generally circular cross-sectional configuration slightly larger than the circular peripheral configuration of the can ends. The peripheral surface of the ends are thus transversely confined in the conduit while being easily movable axially within the conduit. The can ends are stacked into the conduit through an inlet opening and may be pushed or pulled through the conduit passage to an outlet opening into a machine infeed or directly into the machine which is being fed. If the inlet opening is higher than the outlet opening the ends may move by gravity along through the conduit under the weight of the stack. In either case, the ends must exit from the conduit through the outlet opening and into feed apparatus associated with the machine, usually one at a time, but also in some cases, a stack at a time, at a rate consistent with the machine's operation.
In feeding the ends to some machine, if the force moving the ends through the conduit is relatively high, then the ends exiting from the conduit are tightly compressed and it is difficult for the feed apparatus of the machine to separate the ends for performing the required manufacturing operation. If the moving force is too low, then the ends may separate in the conduit and the feed rate into the machine is inconsistent. The ideal situation is for the ends to exit from the conduit one at a time at the desired rate and to feed directly into the machine feed or to stack loosely into the machine's infeed.
To obtain desired feed characteristics, prior art devices have utilized pairs of spring loaded rollers to frictionally engage and grip the peripheral edges of the can ends with the spring tension being adjustable to vary the amount of friction applied to the ends by the rollers. The spring tension on the rollers may be adjusted so that a stack of abutting ends moving through a set of rollers is spread out with spaces between adjacent ends. The ends can then be fed into a machine, such as a tester, one at a time.
Prior art devices of this type, however, have certain disadvantages. The rollers must be accurately positioned in the conduit and the spring tension on the rollers must be set exactly the same or uneven pressure is applied to the can ends. Uneven pressure causes an end to cock and jam between the rollers or in the conduit. Also, even if both rollers apply the same pressure, since pressure is usually only applied at two opposite peripheral portions of the end, the ends still often cock and jam between the rollers. The spring tension and positioning of the rollers therefore must be constantly maintained to insure that the rollers will function properly. In addition, spring loaded devices of this type provide no easy means for completely stopping the flow of ends in the conduit. If the flow of ends into the machine needs to be stopped, a separate brake mechanism is conventionally utilized.
The present invention provides conveyor apparatus with a feed control means that overcomes these prior art limitations and which comprises conveying conduit means defining an elongated passage for conveying articles therethrough; resilient liner means associated with the conduit means and adapted to be forced by fluid pressure into frictional engagement with portions of the peripheral surfaces of articles in the passage; and force applying means associated with the resilient liner means for forcing the resilient means into frictional engagement with articles in the passage. When there is no force or a relatively low level of force applied to the liner means, there is no friction between the liner means and the articles, and the articles will move freely through the conveying conduit means. A relatively high level of force may increase the friction between the liner means and the articles to the point where the feed control acts as a brake and the articles will not pass through. The force may also be regulated so that the friction is such that a gap is drawn between adjacent articles, and the articles exit from the feed control means one at a time for feeding into a machine.
Thus, with the apparatus of the present invention, the friction pressure exerted on the articles can be easily varied to provide an effective means for controlling the flow and feeding of articles in the conveying conduit. While the invention is particularly adapted for conveying articles such as can ends, some of the inventive concepts may be adapted to control movement of other articles such as cans, bottles, boxes, etc.